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Date: Fri, 12 Oct 2007 09:38:00 -0500
From: Dan Nelson <dnelson@allantgroup.com>
To: John Baldwin <jhb@freebsd.org>
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User-Agent: Mutt/1.5.16 (2007-06-09)
Cc: freebsd-current@freebsd.org, Ivan Voras <ivoras@freebsd.org>
Subject: Re: Panic in arpresolve->rt_check?
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In the last episode (Oct 10), John Baldwin said:
> On Wednesday 12 September 2007 02:50:37 pm Ivan Voras wrote:
> > Dan Nelson wrote:
> > > The same panic was also reported for 6.2 via PR 107865 and PR
> > > 112490.  112490 included a workaround patch (I haven't tried it;
> > > just found it).
> > 
> > The proposed patch in kern/112490 looks trivial but someone who
> > knows more about net locking should check it out. Unfortunately it
> > lacks context and I don't know the code in question to apply it
> > safely on a production machine :(
> 
> I also get panics with what appears to be a double free of rt_gwroute
> in rtexpunge(), so I think while this PR may help some with figuring
> out the problem, I'm not sure it solves the root bug.
> 
> Hmm, possibly try this patch:

This makes the panics more frequent on my machine, actually :)
 
> Index: route.c
> ===================================================================
> RCS file: /usr/cvs/src/sys/net/route.c,v
> retrieving revision 1.120
> diff -c -r1.120 route.c
> *** route.c	11 Jun 2007 12:19:34 -0000	1.120
> --- route.c	10 Oct 2007 20:12:54 -0000
> ***************
> *** 1314,1319 ****
> --- 1314,1321 ----
>   				return (ENETUNREACH);
>   			}
>   			RT_LOCK(rt0);
> + 			if (rt0->rt_gwroute != NULL)
> + 				RTFREE(rt0->rt_gwroute);
>   			rt0->rt_gwroute = rt;
>   			if (rt == NULL) {
>   				RT_UNLOCK(rt0);

-- 
	Dan Nelson
	dnelson@allantgroup.com